Shoe press apparatus of a papermaking machine

ABSTRACT

In a shoe press apparatus of a papermaking machine, a press part comprises a roll which serves as a pressing member and a shoe. A belt is sandwiched between the roll and the shoe. A lubricant feeder supplies a lubricant from the outside of the shoe at the upstream side of the shoe. A lubricant holding section, comprising a plurality of grooves is provided on the upstream end of the shoe. Lubricant supplied from the lubricant feeder is held in the lubricant holding section of the shoe, and is more reliably supplied to the press part as the belt runs through the press part. The Structure of the lubricant holding section is comparatively simple, and the lubricant holding section decreases friction, thereby saving energy.

FIELD OF THE INVENTION

[0001] This invention relates to improvements in the shoe pressapparatus of a papermaking machine, and more particularly toimprovements which decrease the friction generated between the shoe anda belt.

BACKGROUND OF THE INVENTION

[0002] In the past, in the press and calender stages of a papermakingprocess, a paper material was typically compressed between a pair ofpress rolls. However, the press rolls apply pressure to the papermaterial only along a narrow line. Therefore, it was difficult toincrease the amount of water squeezed out of the paper material in thepress part. Moreover, since the paper material is flattened at thecalender part, undesirable effects are occasionally produced on themanufactured paper. To avoid these characteristic problems, there hasbeen a trend toward the use of a shoe press apparatus, wherein a pressroll cooperates with a shoe the surface of which conforms to the outersurface of the press roll. The use of the shoe press apparatus has beengrowing recently, and it has come into widespread use.

[0003] FIGS. 7-9 show conventional shoe press apparatuses used in apress stage of a papermaking machine, and FIG. 10 shows a conventionalshoe press apparatus used in the calender stage. Shoe press apparatuses100 a and 100 b, shown in FIGS. 7 and 8 respectively, utilize a presspart P comprising a press roll R and a shoe S. A wet paper web W, a pairof felts F pinching the wet paper web W, and a belt B, are provided inthe press part P. With the rotation of the press roll R, the wet paperweb W, the felts F, and the belt B, run through the press part P. Thearrow MD (“machine direction”) shows the direction of the rotation ofthe press roll R.

[0004] In many cases, a belt B is manufactured by impregnating a basebody comprising a woven fabric, etc., with resin, in order to impartstrength to the belt. Depending on the structure of the shoe pressapparatus, a relatively long belt, as in FIG. 7, or a short belt, as inFIG. 8, may be adopted.

[0005] The shoe press apparatus 10 d, used in a calender part shown inFIG. 10, has a structure corresponding to that of the press part shownin FIG. 8, but with the press roll R replaced by a calender roll R′. Acalender belt BC and paper material W′, having a rough surface, aresandwiched by the press part P comprising the calender roll R′ and ashoe S.′ The belt BC and the paper material W′ pass through the presspart P with the rotation of the calender roll R′. The calender belt BCdiffers in exactness from a press part belt B. However, both belts havethe same basic structure, consisting of a base body and a resin.

[0006] Next, a shoe press apparatus 100 c of FIG. 9 does not use a pressroll. Instead, its press part P comprising a pair of shoes Sa and Sb.This shoe press apparatus is disclosed in Unexamined Japanese PatentPublication No. 131075/1998. In shoe press apparatus 100 c, a wet paperweb (not shown), a pair of felts F, pinching the wet paper web, and apair of belts, Ba and Bb, pass through the press part P, between thepair of shoes Sa and Sb. Belt Ba is a driven belt.

[0007] In these shoe press apparatuses, it is important to decrease thefriction generated between the shoe and the belt while the belt isrunning. In the shoe press apparatuses 100 a, 100 b, and 100 d, shown inFIGS. 7, 8, and 10, the belts B and BC rotate along with the rotation ofthe press roll R or the calender roll R′. Moreover, in the shoe pressapparatus 100 c of FIG. 9, the belt Bb rotates along with the drivenbelt Ba. Decreasing the friction generated between the belts and theshoes will reduce the energy consumed in driving the press roll R, thecalender roll R′, or the driven belt Ba.

[0008] Therefore, it is conventional practice to supply a lubricantbetween a belt and a shoe to decrease the friction generated betweenthem. Oil is usually used as a lubricant, but water or other fluid alsomay be used.

[0009] FIGS. 11-14 show conventional shoe press apparatuses havinglubricant supply structures. FIG. 11 is a partial cross-sectional viewof a shoe press apparatus 100 e, disclosed in Unexamined PCT NationalPhase Publication No. 503561/1997. This shoe press apparatus 100 e has alubricant feeder OS, located on the upstream side of a shoe S, andsupplying a lubricant between the shoe S and a belt B from the outsideof the shoe S in response to a controller.

[0010] In this shoe press apparatus 100 e, the curvature of the surfaceof the shoe S differs from that of the press roll R so that a hollowspace is provided between the shoe S and the roll R, and a lubricantsupplied from outside of the shoe S can accumulate between the shoe Sand the belt B.

[0011]FIG. 12 is a partial cross-sectional view of a shoe pressapparatus 100 f, disclosed in Unexamined PCT International PublicationNo. WO 00/24965. A concave part 60 is provided in the upper surface of ashoe S, and a supply passage 62, for supplying a lubricant to theconcave part 60, is provided in the shoe S, leading from underneath theshoe to the concave part. Therefore, this shoe press apparatus 100 fsupplies a lubricant between the belt B and shoe S from the inside ofthe shoe S. In this connection, although a shoe S comprising twomembers, S′ and S″, is shown in FIG. 12, the shoe may alternatively becomposed of a unitary member.

[0012] Shoe press apparatus 100 g, shown in FIG. 13, is another examplein which a lubricant is supplied between a shoe and a belt from theinside of the shoe. This shoe press apparatus 100 g is disclosed inUnexamined Japanese Patent Publication No. 41486/1990. Two concaveparts, 60 a and 60 b, are formed on the upper surface of the shoe S, anda lubricant is supplied to these concave parts through supply passage 62a and 62 b respectively, both supply passages being provided inside theshoe S. Lubricant supplied to the concave part 60 a provided in thecenter of the shoe S of this shoe press apparatus 100 g also functionsto apply pressure to the belt B.

[0013]FIG. 14 shows a shoe press apparatus 100 h disclosed in UnexaminedJapanese Patent Publication No. 33293/1989. In this shoe pressapparatus, a guide member SA, which may move in an axial direction, isprovided on a shoe S, and a lubricant feeder OS is provided on theupstream of the guide member SA. In this shoe press apparatus 100 h,although the guide member SA is not pressed by a press roll, it formsthe introduction part of the shoe S and may therefore be considered amember forming a part of the shoe S.

[0014] As described in the above, there are several kinds ofconventional shoe press apparatus, either supplying a lubricant from theoutside of the shoe S as shown in FIG. 11, or supplying a lubricant fromthe inside of the shoe S as shown in FIGS. 12-14. All of these shoepress apparatuses are subject to several problems. In the case in whichlubricant is supplied from the outside of the shoe S, it is difficult tosupply the lubricant to the area between the shoe S and belt B, sincethe gap between the shoe and belt is narrow, and lubricant is suppliedwhere the shoe is in contact with the belt. Therefore, althoughlubricant is supplied continuously as a jet so that more lubricant maybe supplied between the shoe S and belt B, it is difficult to achieveadequate lubrication since the lubricant tends to drop off beforereaching the space between the shoe S and the belt B, due to factorssuch as the shape of the end of the shoe S.

[0015] On the other hand, in the case in which lubricant is suppliedthrough the shoe, there is a different problem. Even though a sufficientquantity of lubricant is supplied to the interface between the belt andthe shoe on the downstream side of the concave part of the shoe, little,if any lubricant is supplied to the upstream side. Moreover, althoughthe apparatus shown in FIG. 13 partially solve this problem by supplyinga lubricant at two points its manufacturing cost is relatively highsince the interior structure of the shoe, and the structure of relatedcomponents, are complex.

SUMMARY OF THE INVENTION

[0016] The shoe press apparatus in accordance with the invention has apress part comprising a shoe, a pressing member cooperating with, and inopposed relationship to, the shoe, a belt sandwiched in the press partbetween the shoe and the pressing member and movable relative to saidshoe in a first direction from an upstream side of the shoe toward adownstream side of the shoe. The belt is arranged to come into contactwith the shoe at a location on the upstream side, and a lubricant supplymeans is arranged to supply lubricant to the shoe and belt on theupstream side of the shoe. The improvement comprises a lubricant holdingsection formed in the surface of the shoe at least in part on theupstream side of said location.

[0017] The lubricant holding section may be provided in an area of theshoe that is not contacted by said belt. Alternatively, part of thelubricant holding section may be provided in an area that is notcontacted by the belt while a part of the lubricant holding section isprovided in an area that is contacted by said belt.

[0018] The lubricant holding section may comprises a plurality of minuteconcavities, or one or more grooves. In the case of a groove, the groovecan become shallow, or wider, or both shallower and wider, toward itsdownstream end. The upstream end of the groove may have an opening, ormay be closed. The lubricant held in the lubricant holding section ofthe shoe is reliably supplied to the press part, between the shoe andthe belt, along substantially the entire area over which the belt andshoe are in contact with each other while the papermaking machine isoperating. Consequently, the lubricant decreases the friction betweenthe belt press shoe to a greater degree than in conventional shoepresses.

BRIEF DESCRIPTION OF DRAWINGS

[0019]FIG. 1(a) is a partial sectional view of the press part of apapermaking shoe press apparatus according to an embodiment of theinvention;

[0020]FIG. 1(b) is a partial perspective view showing the upstream sideof a shoe;

[0021]FIG. 2(a) is a partial cross-sectional view of the upstream partof a press part corresponding to FIG.1, wherein a lubricant holdingsection is provided in a portion of the shoe that is not contacted bythe belt;

[0022]FIG. 2(b) is a partial cross-sectional view of the upstream partof a press part corresponding to FIG.1, wherein a part of a lubricantholding section is provided in a portion of the shoe that is notcontacted by the belt, and another part of the lubricant holding sectionis provided in a portion of the shoe that is contacted by the belt;

[0023]FIG. 3 is a partial perspective view of a shoe in accordance withanother embodiment of the invention;

[0024]FIG. 4 is a partial top plan view of a shoe in accordance withstill another embodiment of the invention;

[0025]FIG. 5(a) is a partial perspective view of a shoe in accordancewith a further embodiment of the invention;

[0026]FIG. 5(b) is schematic cross-sectional view of the shoe of FIG.5(a);

[0027]FIG. 6 is a partial perspective view of a shoe having a lubricantholding section which is not composed of grooves; FIG. 7 is a schematicelevational view of a first conventional shoe press apparatus;

[0028]FIG. 8 is a schematic elevational view of a second conventionalshoe press apparatus;

[0029]FIG. 9 is a schematic elevational view of a third conventionalshoe press apparatus;

[0030]FIG. 10 is schematic elevational view of a conventional shoe pressapparatus used as a calender part of a papermaking machine;

[0031]FIG. 11 is a partial cross-sectional view of a conventional shoepress apparatus having a lubricant supply structure upstream of theshoe;

[0032]FIG. 12 is a partial cross-sectional view of another conventionalshoe press apparatus having a lubricant supply structure within theshoe;

[0033]FIG. 13 is a partial cross-sectional view of another conventionalshoe press apparatus having a lubricant supply structure within theshoe; and

[0034]FIG. 14 is a partial cross-sectional view of still anotherconventional shoe press apparatus having a lubricant supply structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In the shoe press apparatus 10 shown in FIG. 1(a), which may be aeither a press or a calendar, the press part P comprises a roll R,serving as a pressing member, and a shoe S1, the shape of which conformsto the outer surface of the roll R. A conventional press roll orcalender roll may be used as the roll R. Paper material (not shown), anda belt-shaped body such as a pair of felts (not shown) for pinching thepaper material, are pinched in the press part P along with a belt B.When the roll R rotates in the direction of arrow MD, the papermaterial, the felts, and the belt B pass through the press part P.

[0036] A lubricant feeder OS, supplying a lubricant between the belt Band the shoe S1 is provided upstream of the shoe press apparatus 10, theterm “upstream” referring to a location of a portion of the belt justbefore it enters the press part of the machine in the running directionof the machine, i.e. the machine direction MD. The lubricant feedershown in FIG. 11 may be used as the lubricant feeder OS.

[0037] As shown in FIG. 1(b), a lubricant holding section 20 is providedon the upstream end of the shoe. Grooves 30, each comprising a bottom32, sides 34, a front opening 36, and a back wall .38, are provided inthe upstream end of the shoe S1. The grooves 30 are disposed in parallelrelationship along the upstream end of the shoe, and lands 40 are formedbetween the grooves. Although not illustrated in FIG. 1(b), the edges ofthe grooves 30 are rounded off.

[0038] A lubricant, supplied between the belt B and the shoe S1, is heldbetween the grooves 30 and the belt B, as well as in an area where thebelt B is in contact with the land 40. The lubricant held between thebelt B and the lands 40, or between the grooves 30 and the belt B, isdrawn into the press part P (between the belt B and the shoe S1) by therunning of the belt B. A part of the lubricant supplied between the beltB and the lands 40 may drop off occasionally as in the case of aconventional shoe press lubricated from the upstream side. However, thelubricant supplied between the grooves 30 and the belt B is morereliably drawn into the press part P by the running of the belt B, andconsequently more lubricant is supplied to the press part P than before.

[0039] In the shoe press apparatus 10 according to the invention lessfriction is generated between the belt B and the shoe S than in the caseof a conventional shoe press. Consequently less energy is required todrive the belt, and the energy required for rotating and driving theroll R is decreased. The location of the lubricant holding section 20 ofshoe S1 will be explained referring to FIG. 1(a). L1 is the locationwhere the belt B comes into contact with the shoe S1, and L2 is thelocation of the upstream end of the of the press part P, where the rollR and shoe S begin to apply pressure to the belt. As showndiagramatically in FIG. 1(a), the lubricant holding section may beprovided in any of three areas: an area a which extends from an upstreamlocation, where the shoe S is not in contact with the belt B, to thelocation L1; an area b, which extends from an upstream location wherethe shoe S is not in contact with the belt B to a location downstream oflocation L1; and an area c which extends from an upstream location wherethe shoe S is not in contact with the belt B to the location which iseither coincident with, or on the downstream side of, location L2.

[0040]FIG. 2(a) shows a case where the lubricant holding section 20 isprovided in the above-mentioned area a, and FIG. 2(b) shows a case wherethe lubricant holding section 20 is provided in the above-mentioned areac. In the case where the lubricant holding section 20 is in area a, asshown in FIG. 2(a), lubricant can be reliably supplied to the press partP, since the lubricant is held in shoe S1″ immediately upstream of thelocation at which the belt B comes into contact with the shoe. On theother hand, where the lubricant holding section 20 is provided in theabove-mentioned area c, as shown in FIG. 2(b), lubricant may be held inthe area where the belt B is in contact with the shoe S1″, as well asimmediately upstream of the location at which the belt B comes intocontact with the shoe S1″. Moreover, when the lubricant holding section20 is in area b, and also when it is in area c, lubricant will be heldin an area where the belt B is in contact with the shoe S1″. Therefore,in these cases, lubricant is also reliably supplied to the press part P.The choice of which of the areas a, b, and c the lubricant holdingsection 20 is provided in is made according to the inclination of therounded-off edge of the shoe S1 and the location where the belt B comesin contact with the shoe, the contact angle between the belt B and theshoe S1, and the distance between the contact starting location L1 andthe upstream end L2 of the press part

[0041] It is not necessary that the grooves forming the lubricantholding section be uniform in depth or that they have a back wall.

[0042] In the embodiment shown in FIG. 3, a lubricant holding section22, on a shoe S2, is composed of grooves 30 a, each having a bottom 32a, sides 34 a, a front opening 36 a, and a back 38 a. Lands 40 a, whichextend in the running direction of the belt over the shoe, are providedbetween the grooves at the upstream end of the shoe. The depths of thesegrooves 30 a gradually becomes shallow from the front opening 36 atoward the back 38 a. The shoe S2 of this embodiment tends to maintain amore stable running condition, since the difference in level between thelands 40 a and the bottoms of the grooves is small at the location wherethe belt B comes into contact with the shoe.

[0043] In FIG. 4, a lubricant holding section 24 comprises grooves 30 b,each of which has a bottom 32 b, sides 34 b, a front opening 36 b, and aback 38 b. Lands 40 b are formed between the grooves. As in the shoe ofFIG. 3, the depths of each of the grooves 30 b in FIG. 4 graduallybecomes shallow from the front opening 36 b toward the back 38 b. Theback 38 b of each groove is wider than its front opening 36 b. Thelubricant holding section 24 of this embodiment can supply morelubricant into the press part P, since more lubricant is held where thebelt B is in contact with the shoe S3. On the other hand, as analternative, in the lubricant holding section the width of the back ofeach groove may be narrower than the width of its front opening. In thiscase, friction generated where the belt B comes into contact with theshoe cab be decreased.

[0044] In the embodiment illustrated in FIGS. 5(a) and 5(b), a lubricantholding section 26 comprises grooves 30 c wherein a wall 50 is providedinstead of a front opening as in the embodiment of FIG. 3. The wallstructure dams up lubricant, preventing it from dropping off the groove30 c. Since lubricant is always held in the groove 30 c, more lubricantmay be supplied continuously between a belt and shoe S4.

[0045] The lubricant holding section is not necessarily grooved. Forexample, in FIG. 6 a shoe S5 has, at its upstream end, a lubricantholding section 28 comprising many minute concavities 30 d (usuallycalled a “satin finish” in machining). In this case, a large amount oflubricant supplied from the outside to the shoe S5 can be held in themultitude of minute concavities 30 d, and therefore a large amount oflubricant can be supplied continuously between a belt and shoe S5.

[0046] In a shoe press apparatus according to the invention, theabove-described lubricant holding sections 20, 22, 24, 26 and 28 may beprovided shoes of various shapes. In this case, the structure of thelubricant holding sections, and the positions where the lubricantholding sections are provided, differ according to the shape of theshoe, so that lubricant supplied from the outside of the shoe can beheld most effectively. Therefore, it is necessary to provide lubricantholding sections of a suitable structure, and in a suitable position,for the shape of a shoe. For instance, when a shoe comprises a pluralityof members as in the case of the conventional shoe press apparatus shownin FIG. 12, a lubricant holding section may be provided in the shoemember on the upstream side of the apparatus. Moreover, when anauxiliary member, such as a guide member corresponding to guide memberSA in FIG. 14, is provided at the upstream of a shoe a lubricant holdingsection may be provided in this auxiliary member.

[0047] Although the invention has been described with reference to shoepresses utilizing rolls as pressing members, the invention may be alsobe applied to a shoe press apparatus of the kind shown in FIG. 9,wherein the press part comprises a pair of shoes corresponding to shoesSa and Sb. In this case, since the upper shoe corresponds to a pressingmember, a lubricant holding section may be provided in a suitableposition of the lower shoe. Needless to say, a lubricant holding sectionmay also be provided on the upper shoe.

[0048] In accordance with the invention, a shoe press apparatus for apapermaking machine according to the invention can, with a comparativelysimple structure, reliably supply a lubricant from the outside of a shoeto a press part. Therefore, friction generated between a belt and theshoe can be decreased significantly , and, as a result, the energyrequired to drive the belt can also be decreased significantly.Moreover, since the structure is relatively simple, it can be applied toshoe presses of various structures without greatly increasing theirmanufacturing cost.

What is claimed is:
 1. A shoe press apparatus for a papermaking machine,said shoe press apparatus having a press part comprises a shoe, apressing member cooperating with, and in opposed relationship to, saidshoe, a belt sandwiched in said press part between said shoe and saidpressing member and movable relative to said shoe in a first directionfrom an upstream side of the shoe toward a downstream side of the shoe,said belt being arranged to come into contact with the shoe at alocation on said upstream side, and a lubricant supply means arranged tosupply lubricant to said shoe and belt on the upstream side of the shoe,wherein the improvement a lubricant holding section formed in thesurface of the shoe at least in part on the upstream side of saidlocation.
 2. A shoe press apparatus as claimed in claim 1, wherein saidlubricant holding section is provided in an area of the shoe that is notcontacted by said belt.
 3. A shoe press apparatus as claimed in claim 1,wherein part of said lubricant holding section is provided in an areathat is not contacted by said belt and a part of said lubricant holdingsection is provided in an area that is contacted by said belt.
 4. A shoepress apparatus as claimed in claim 1, wherein said lubricant holdingsection comprises a plurality of minute concavities.
 5. A shoe pressapparatus as claimed in claim 1, wherein said lubricant holding sectioncomprises a groove.
 6. A shoe press apparatus as claimed in claim 5,wherein said groove has upstream and downstream ends, and becomesshallow toward the downstream end of the groove.
 7. A shoe pressapparatus as claimed in claim 5, wherein said groove has upstream anddownstream ends, and becomes wider from the upstream end of the groovetoward the downstream end of the groove.
 8. A shoe press apparatus asclaimed in claim 5, wherein said groove has upstream and downstreamends, and wherein the upstream end of said groove has an opening.
 9. Ashoe press apparatus as claimed in claim 5, wherein said groove hasupstream and downstream ends, and wherein the upstream end of saidgroove is closed.
 10. A shoe press apparatus as claimed in claim 5,wherein said groove has upstream and downstream ends, and becomes bothshallower and wider toward the downstream end of the groove.
 11. A shoepress apparatus as claimed in claim 5, wherein said groove has upstreamand downstream ends, and becomes shallow toward the downstream end ofthe groove, and wherein the upstream end of said groove has an opening.12. A shoe press apparatus as claimed in claim 5, wherein said groovehas upstream and downstream ends, and becomes both shallower and widertoward the downstream end of the groove, and wherein the upstream end ofsaid groove has an opening.
 13. A shoe press apparatus as claimed inclaim 5, wherein said groove has upstream and downstream ends, andbecomes wider from the upstream end of the groove toward the downstreamend of the groove, and wherein the upstream end of said groove has anopening.
 14. A shoe press apparatus as claimed in claim 5, wherein saidgroove has upstream and downstream ends, and becomes shallow toward thedownstream end of the groove, and wherein the upstream end of saidgroove is closed.
 15. A shoe press apparatus as claimed in claim 5,wherein said groove is provided in an area of the shoe that is notcontacted by said belt.
 16. A shoe press apparatus as claimed in claim15, wherein said groove has upstream and downstream ends, and becomesshallow toward the downstream end of the groove.
 17. A shoe pressapparatus as claimed in claim 15, wherein said groove has upstream anddownstream ends, and becomes wider from the upstream end of the groovetoward the downstream end of the groove.
 18. A shoe press apparatus asclaimed in claim 15, wherein said groove has upstream and downstreamends, and wherein the upstream end of said groove has an opening.
 19. Ashoe press apparatus as claimed in claim 15, wherein said groove hasupstream and downstream ends, and wherein the upstream end of saidgroove is closed.
 20. A shoe press apparatus as claimed in claim 1,wherein said lubricant holding section comprises a groove and whereinpart of said groove is provided in an area that is not contacted by saidbelt and a part of said groove is provided in an area that is contactedby said belt.